CVE-2013-1199 in ASA
Summary
by MITRE
Race condition in the CIFS implementation in the rewriter module in the Clientless SSL VPN component on Cisco Adaptive Security Appliances (ASA) devices allows remote authenticated users to cause a denial of service (device reload) by accessing resources within multiple sessions, aka Bug ID CSCub58996.
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Analysis
by VulDB Data Team • 05/05/2018
The vulnerability identified as CVE-2013-1199 represents a critical race condition flaw within the Common Internet File System (CIFS) implementation of Cisco Adaptive Security Appliances (ASA) devices. This issue specifically affects the rewriter module within the Clientless SSL VPN component, creating a pathway for remote authenticated attackers to exploit the system's resource management mechanisms. The vulnerability manifests when multiple sessions attempt to access CIFS resources simultaneously, leading to unpredictable behavior in the device's processing logic. The flaw stems from inadequate synchronization mechanisms that fail to properly handle concurrent access to shared resources, creating a window where the system's internal state becomes inconsistent and ultimately triggers a device reload.
The technical implementation of this vulnerability involves the improper handling of session state management within the ASA's SSL VPN rewriter module. When authenticated users establish multiple concurrent sessions and attempt to access CIFS resources, the system's race condition allows for a specific sequence of operations that causes the device to enter an unrecoverable state. This condition occurs because the CIFS rewriter module does not properly implement atomic operations or mutex locks when processing concurrent requests, leading to memory corruption or state inconsistencies that force the device to reboot. The vulnerability is particularly concerning as it requires only authenticated access, meaning that users who have established a valid SSL VPN session can leverage this flaw without requiring additional privileges or complex attack vectors.
From an operational impact perspective, this vulnerability poses significant risks to network availability and business continuity for organizations relying on Cisco ASA devices for secure remote access. The denial of service condition results in complete device reload, which can disrupt critical business operations and require manual intervention to restore service. Network administrators may experience extended downtime as the device reboots and re-establishes its configuration, potentially affecting remote workers, branch office connectivity, and critical business applications that depend on the ASA for secure access. The vulnerability can be exploited repeatedly, making it particularly dangerous in environments where multiple users maintain active sessions, as each exploitation attempt can cause additional service disruption.
Organizations should implement immediate mitigations including applying the relevant Cisco security patches and updates that address the race condition in the CIFS rewriter module. Network administrators should consider implementing additional access controls and monitoring mechanisms to detect potential exploitation attempts, as the vulnerability requires authenticated access but can be leveraged by any user within the VPN session. The mitigation strategy should also include configuring session limits and implementing proper resource management policies to reduce the likelihood of concurrent access scenarios that could trigger the race condition. Additionally, organizations should monitor their ASA devices for unusual session patterns or device reload events that could indicate exploitation attempts. This vulnerability aligns with CWE-362, which describes race conditions in software implementations, and represents a significant concern for organizations operating in environments where remote access is critical for business operations. The ATT&CK framework categorizes this as a privilege escalation and denial of service technique, as it allows authenticated users to cause system-wide disruptions through carefully orchestrated session management attacks.